IPPC climate change expert

To the Editor:
Columnists such as Kevin O'Brien and George Will take apparent pleasure in
criticizing climate-change science. I am forced to conclude, however, that
they are largely ignorant of the topic.

As an environmental engineer with a Ph.D., I know enough about science and technology to realize that I am not a climate-change expert. So, I get my information on climate change from the most expert, thorough and impartial group of climate change experts on the planet, the Intergovernmental Panel on Climate Change (IPPC). I wish news commentators would follow a similar course.

The IPPC, on the Web at www.ipcc.ch, is an international body of the best
climate scientists that reviews all of the relevant studies and periodically
reports on the state of the Earth's climate. Reports are published every 6
years. The last IPCC report came out in 2007.

The IPCC is a very conservative group, in the scientific sense. They only
make conclusions that are supported by the evidence. In each report, they
have found that the previous report was too conservative, in that climate
change advanced more than they predicted.

The 2007 report is based on studies that observed more than 30,000
significant changes in the Earth's physical and biological systems. Of those
30,000 changes, over 90 percent are consistent with global warming. Yes,
that means that not all observations are consistent with global warming,
just the overwhelming majority.

The 2007 IPCC report stated that warming of the climate system is
unequivocal and that most of the observed increase in global average
temperatures, since the mid-20th century is very likely due to observed
increases in anthropogenic greenhouse gas concentrations.

"Very likely" has a statistical meaning: The scientists are 95 percent
confident that the observed increase is human caused. For conservative
scientists, that is about as certain as something as complicated as climate
change can get.

Unscientific people, including writers such as Will and O'Brien, are easily
confused when confronted with cherry-picked studies, controversies over a
small number of climate-change studies or stolen e-mails taken out of
context.